1. Field
Apparatuses consistent with exemplary embodiments relate to a surface plasmon polariton modulator, and more particularly, to a surface plasmon polariton modulator capable of locally varying a physical property of a dielectric material to control a surface plasmon polariton.
2. Description of the Related Art
A charge-density oscillation at an interface between a metal layer and a dielectric layer is referred to as a surface plasmon polariton or simply a surface plasmon. Since the surface plasmon has a fast propagation velocity that is approximate to a velocity of light and has a high frequency reaching infrared rays, visible rays, and ultraviolet rays, the surface plasmon is appropriate for high-bandwidth communications.
A wavelength of light of about 102 nm to about 103 nm, used in optical elements, is much greater than a size of an element of a high-integration electronic circuit. Therefore, integration is reduced in an optoelectronic integrated circuits (OEICs), which uses light without wavelength conversion, due to the relatively long wavelength. A surface plasmon may have a shorter wavelength than an electromagnetic wave having the same frequency. Thus, since an OEIC may be realized using the above-stated property of surface plasmons, surface plasmons have attracted much attention in this field.
Optical methods are used to generate a surface plasmon. For example, when a thin metal film is coated on a dielectric having a refractive index greater than 1 and light illuminates the thin metal film through the dielectric at a particular angle, a surface plasmon having a particular frequency can be strongly and resonantly generated. According to another method of generating a surface plasmon, a diffraction grating, a hole, a crack, or a groove is formed in a smooth metal surface, and then light illuminates the smooth metal surface. However, the above-described methods use light to generate the surface plasmon and thus require an additional external light sources. Therefore, the method is not appropriate for use on an integrated circuit. A method of electrically generating a surface plasmon based on silicon nanoparticles and a method of electrically sensing a surface plasmon have been introduced.
A technique for converting an electric signal into a surface plasmon and a technique for converting a surface plasmon into an electric signal are the most basic elements in a surface plasmon-based OEIC technique. However, a technique for controlling a surface plasmon using an electric signal is further required to realize an OEIC based on the surface plasmon. For example, a surface plasmon polariton modulator may be a basic component of a plasmon-based optical part and may be applied as a surface plasmon-based optical modulator, a basic element of an OEIC technique, or the like.